Adults who reduced their daily sleep by approximately 80 minutes experienced an increase in body weight and waist circumference after six weeks, according to a recent study.

The study also found that while sleep deprivation increased the time spent awake, it also led to a rise in sedentary time, where individuals remained sitting or inactive.

A research team led by Professor Marie-Pierre St-Onge at the Columbia University Vagelos College of Physicians and Surgeons announced the results of a clinical trial involving adults at risk for cardiometabolic disease in the Annals of Internal Medicine, a journal of the American College of Physicians, on July 7 (local time).

While the link between sleep deprivation and obesity has been known, most previous studies were conducted over short periods under extreme conditions, such as limiting daily sleep to about four hours.

Consequently, the impact of chronic, mild sleep deprivation on body weight had not yet been clearly established.

The research team examined the effects of long-term, mild sleep deprivation on 95 adults who typically sleep seven hours or more per day.

Participants underwent two six-week periods separated by a washout interval: one where they maintained their normal sleep schedule, and another where they delayed their bedtime to reduce their nightly sleep by one and a half hours.

The researchers then used wrist-worn monitors to measure physical activity and compared changes in biomarkers such as body fat mass.

The results showed that during the sleep-restricted period, actual sleep time decreased by an average of 78.4 minutes per day, while body weight increased by an average of 0.45 kilograms and waist circumference by an average of 0.52 centimeters.

Furthermore, although the reduction in sleep increased the time spent awake, the average daily time spent sitting or inactive increased by 17.2 minutes. In particular, men and postmenopausal women showed an increase in sedentary time of up to 30 minutes per day on average.

The researchers warned, "While the weight gain over six weeks may seem small in terms of numbers, if this sleep pattern continues for a year, it could lead to significant weight gain."

They also explained, "These results suggest that sleep deprivation may increase the risk of obesity-related diseases such as type 2 diabetes and heart disease."

They added, "Getting enough sleep can help reduce the risk of disease," and emphasized that "further research is needed to determine the specific effects of sleep improvement on health."

◆ Source: Annals of Internal Medicine, Marie-Pierre St-Onge et al., 'Skimping on Sleep and Its Impact on Body Weight and Composition: A Pooled Analysis of Randomized Trials', https://www.acpjournals.org/doi/10.7326/ANNALS-25-01660